1. Field of Disclosure
Embodiments of the disclosure relate generally to methods and apparatus for providing uninterruptible power to sensitive and/or critical loads. More specifically, embodiments of the disclosure relate to racks used to house components of uninterruptible power supplies.
2. Discussion of Related Art
Centralized data centers for computer, communications and other electronic equipment have been in use for a number of years, and more recently, with the increasing use of the Internet, large scale data centers that provide hosting services for Internet Service Providers (ISPs), Application Service Providers (ASPS) and Internet content providers are become increasingly popular. It is often desirable to operate equipment within data centers seven days a week, 24 hours per day, with little or no disruption in service. To prevent any disruption in service, it is common practice in data centers to use uninterruptible power supplies (UPSs) to ensure that the equipment within the data centers receives continuous power throughout any black out or brown out periods. Typically, data centers are equipped with a relatively large UPS at the main power distribution panel for the facility. Often, the UPS is selected to have sufficient capacity to meet the power requirements for all of the equipment within the facility.
For example, equipment within data facilities in the United States may have 120 volt or 208 volt input power requirements, and a power distribution unit having a step down transformer is often used between the output of the UPS and power feeds for equipment racks to lower a 480 volt input voltage to 120 volts or 208 volts for the equipment racks. A circuit breaker panel is typically either installed in the PDU or mounted near the PDU. In countries outside the United States, equipment racks may be configured for equipment having different or varying power requirements.
There are several drawbacks with the traditional design of data centers. One drawback in the design of traditional data centers involves the difficulty in selecting the size of a UPS for the facility. As briefly discussed above, many newer data centers are used as web hosting facilities that essentially lease space and utilities to Internet content providers or Internet Service Providers. Often when these data centers are initially designed, the final power requirements for the facility are not known, and it is often not for some time, if ever, that a facility becomes fully occupied. If the UPS is selected for full capacity, and the facility is operated at substantially below full capacity for some time, then the overhead costs of the facility may become undesirably high due to the cost of the UPS. Further, there are power losses associated with a UPS. If a UPS is operated at substantially below full capacity, then these losses may become significant when compared with the total power consumption of the facility. If a UPS for a facility is selected for less than full capacity, then it may have to be replaced, at considerable cost, when the usage of the facility increases.
Today's three-phase UPS systems are typically based on a highly integrated rack-based frame. The rack may consist of firmly installed hardware and removable modules. Batteries are sometimes mounted in separate dedicated frames, and for smaller systems, the batteries may be mounted in the same frame, but in fixed battery positions. The typical approach, while providing a very robust and complete UPS system for a given power range, requires that the customer of the UPS system pay a premium price for a full system, even if the requirements placed on the UPS system are below the maximum capacity of the system.